Viewports not receiving mouse _input events if they're not overlapping the center of the game window

Godot Version

4.4.1

I’m trying to add splitscreen to my game. If a SubViewport’s size doesn’t cover the center of the screen, then all mouse _input events for that viewport are ignored. This is with Input.mouse_mode = Input.MOUSE_MODE_CAPTURED

Does anyone know what could be causing this or a potential fix?

MOUSE_MODE_CAPTURED does hide the mouse and lock it to the center of the screen, maybe you will need to use MOUSE_MODE_CONFINED_HIDDEN and warp_mouse every frame to emulate MOUSE_MODE_CAPTURED in a different quadrant of the screen? I’m not seeing a way to change the captured lock position easily.